In the weeks leading up to the 2004 general election, I had several arguments with Republican friends, acquaintances, and neighbors about the choice between Kerry and Bush. Most of these arguments were about the Iraq War, and I didn't make headway on much (immorality, criminal activity, deliberate sabotaging of federal agencies, fiscal irresponsibility) with these committed Republicans.
But there was one argument that did sink in. These Ohio Republicans were worried that George W. Bush lacked one crucial virtue of a president: competence. They happened to believe John Kerry did not demonstrate competence either, but they were worried about their own guy.
In the years since, the price of an incompetent president has grown more dear to the people of the United States; so much so that competence threatens to become an issue in the 2008 presidential race.